Electrical circuit



Aug. 18, 1936. s. RUBEN ELECTRICAL CIRCUIT Filed July 25, 1931 2 Sheets-Sheet 1 INVENTOR SAMUEL RUBEN BY H /S ATTORNEY Aug. 18, 1936. s RUBEN 2,051,396

ELECTRICAL CIRCUIT Filed July 25, 1931 2 Sheets-Sheet 2 I 8 4 l I I 4||||||||l||||:5

INVENTOR SAMUEL RUBEN BY' H ATTORNEY Patented Aug. 18, 1936 UNITED STATES PATENT OFFICE ELECTRICAL CIRCUIT Application July 25, 1931, Serial No. 553,052 1 Claim. ((1250-27) This invention relates to an improvement in an electrical circuit, for the amplification of electrical oscillations. It is a continuation in part of that described in my co-pending application bearing Serial Number 426,828, filed February 8, 1930, Patent No. 1,815,931, July 28, 1931, Re. 18,367, March 1, 1932. An object of this invention is the provision of a vacuum tube circuit having a high amplification factor with a large power output.

Broadly, my invention consists 01' an arrangement of vacuum tubes inan electrical circuit so connected that a tube, connected in the input circuit and another in the output circuit are so interconnected that the second tube produces an amplified response to the energy applied to the input electrodes of the other tube. The elements of the second tube are indirectly coupled to the input circuit through the output circuit of the elements of the first tube. .By such a connection it is possible to obtain an energy output which is undistorted and of high density.

In my said earlier application I have described a tube having a duplicate set of tube elements interconnected as defined, and the circuit in which the tube is connected. But in the circuit of the present invention the elements are in two tubes, the grid of the second tube being directly connected with the cathode of the tube in the input circuit.

Reference is made to the accompanying drawings which illustrate an embodiment of the prior invention and also the novel arrangement of two tubes in an electrical circuit. Fig. 1 represents a vacuum tube containing the duplicate set of elements and having parts of the plate elements so cut away as to better show its construction; Fig. 2 illustrates a plan view if the tube containing the two sets of elements at 22; Fig. 3 represents a section view of those two cathodes and of the heater element, together with an insulating block separating the cathodes; Fig. 4 shows a circuit in which the tube device, having a duplicate set of elements, is connected. Fig. 5 shows the arrangement of two tubes in an electrical circuit.

In Fig. 1, I represents an evacuated glass envelope, 2 the hairpin heater element coated with a refractory insulating oxide, 3 an oxide coated cylindrical cathode supported by conductor wire it. passing through glass rod 6, from which latter a hook suspends element 2. The lower cathode is represented at 31 which is insulated from the upper cathode by insulating member 3e. The upper grid is represented by 4, supported by rods in. These rods are suspended from glass rod 6,

and one of the supporting rods; in has a terminal outlet at t. The upper plate 5 is supported by rods 51; and 5c, the latter having a terminal at St.- The lower cathode 31, is supported by red 3d. having a terminal at St; the lower grid 4., supported by rods 4c, is connected by conductor 4:, with the upper cathode 3. The lower plate ele ment 5a, is supported by rods 5e and 5d, with a terminal outlet at 50. Corresponding elements in Figs. 1, 2, 3, 4, and 5 are indicated by like 10 numerals.

In the circuit shown in Figs. 4 and 5, at B is a battery for biasing the cathode negative in respect to the heater element (in Fig. 5 heater elements) which latter is heated from transformer 15 H. At B1 is a source of plate potential for obtaining the plate current, C being a by-pass condenser in the output circuit (Fig. 4 T represents a translating device and B2 a battery for maintaining the input grid negative with respect to cathode 3). The connection between the cathode of the input circuit tube with the grid of the other tube is indicated at k. In Fig. 4 R is a resistance. The other elements of the circuit correspond to those in the usual arrangement of like circuits.

It is obvious that the cathode elements may be heated directly instead of as indicated in the drawings.

The operation of a circuit containing the single tube with the duplicate set of elements is the same as that containing two separate tubes, the grid of the second tube being connected with the cathode of the first tube, a common source of, potential being provided for the two anodes with a potential difference existing between the two anodes due to the load impedance in the output circuit, as illustrated. However, the operation of the device will be described in relation to the circuit having the single tube. When the cathodes 3 and 3. are heated, they emit electrons ac- 40 celerated by the plate potential from battery B1. This causes a plate current to flow between the input cathode and the adjacent plate and a current between the output cathode and the adjacent grid. That is, there are two electron discharges, 45 one from the input cathode to. its cooperating plate, the other from the other cathode to the grid interposed between it and its cooperating anode, this being equivalent to two electron discharges in series, at a single plate potential. The higher density discharge is between the second cathode and its adjacent plate element. As the lower grid is in the current discharge circuit of the upper electron discharge. and as its potential is governed by the density of the upper electron discharge-any modulation of this electron discharge by the control grid, having such a form as to give a high amplification constant, causes a variation in the high density, lower electron discharge. If the electron emission from the upper cathode is varied by modulation by the change of potential of the upper or input grid by impressed oscillations, the positive potential 01 the lower grid varies accordingly, and as this potential controls the electron emission between the lower cathode and its adjacent plate, an amplified current change occurs in the output circuit. In respect to the number of turns and its biasing to reduce the potential on the second grid, the same preference exists as to the first grid, as mentioned in the earlier application. Likewise, the second grid may have fewer turns to ofler a low impedance path between that cathode and its cooperating anode.

What I claim is:

An electrical circuit having connected therein a control triode and an output triode each triode unit comprising a cathode, a control element and an anode, a heater element for the cathodes, the heater element being separated from the cathodes by a dielectric element, means for biasing the grid of the control triode negatively with respect to the cathode of its triode, a common source of heat energy for both cathodes, in combination with means for negatively biasing the cathode of the output triode with respect to the said heater element, and having a translating device directly connected with the anode of the output triode.

SAMUEL RUBEN. 

